Redhat5.5 cannot create logical partitions !!!

Redhat5.5 cannot create logical partitions !!! -- Linux general technology-Linux technology and application information. For details, refer to the following section. The system/dev/sdc device partitions are as follows:
Total size: 322.1 GB. An extended partition is created, and 14 other logical partitions are created. A total of 39162 cylinders are created before 5844 cylinders are used. There is still a lot of space, no more logical partitions can be created !! Please give me some advice. Thank you!

Disk/dev/sdc: 322.1 GB, 322122547200 bytes
255 heads, 63 sectors/track, 39162 cylinders
Units = cylinders of 16065*512 = 8225280 bytes

Device Boot Start End Blocks Id System
/Dev/sdc1 1 39162 314568733 + 5 Extended
/Dev/sdc5 1 32 256977 83 Linux
/Dev/sdc6 33 64 257008 + 83 Linux
/Dev/sdc7 65 96 257008 + 83 Linux
/Dev/sdc8 97 159 506016 83 Linux
/Dev/sdc9 160 222 506016 83 Linux
/Dev/sdc10 223 472 2008093 + 83 Linux
/Dev/sdc11 473 722 2008093 + 83 Linux
/Dev/sdc12 723 1574 6843658 + 83 Linux
/Dev/sdc13 1575 4614 24418768 + 83 Linux
/Dev/sdc14 4615 4627 104391 83 Linux
/Dev/sdc15 4628 5844 9775521 83 Linux
--------------------------- Only primary partitions can be created.
[Root @ localhost ~] # Fdisk/dev/sdc

The number of cylinders for this disk is set to 39162.
There is nothing wrong with that, but this is larger than 1024,
And coshould in certain setups cause problems:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(E.g., dos fdisk, OS/2 FDISK)

Command (m for help): n
Partition number (1-4 ):
--------------------------- If the other device/dev/sdd is the same, you can create a logical partition as follows:
Command (m for help): n
Command action
L logical (5 or over)
P primary partition (1-4)